From patchwork Thu Aug 22 10:14:34 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Rutland X-Patchwork-Id: 13773188 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C68F0C3DA4A for ; Thu, 22 Aug 2024 10:21:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=BRGYZGWAsRKxoVBkorcLy2yS8clJHeICcoQgGAYJGoA=; b=XVjZsewLfA4JPDpAyVhOERKOlM Iros70xgA8y11RJbIN4bwQxoXUp8vsvD/Xx8j0sZmCQC++PwvlBJN23akJTHFjWPMazMftW0aUuIj SUsiAS907XMhRcUFJWrAZu2IE/QG/g6f9JwlM3C3RO5D+/UGf5W5K6HqcBwYU4qdYSfMDnWfyjSHi vCgR+K49mkz4QY9578N7fg8Xv/3hcgKSa7aV4giF3+9oOQ0Vs26RYuiUQV7VOF4gqRUTtBwYUX+At ehHXuqN6AYV24ZoJI8aPsABRqVfWZ5g5p5i488d2S+KRz5v+R1xhwXhsU7Hxiw2aLEpChclRBb3UC Qb0sF4Ig==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sh4wq-0000000CPUZ-3sW3; Thu, 22 Aug 2024 10:21:44 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sh4r7-0000000COHg-0ISV for linux-arm-kernel@lists.infradead.org; Thu, 22 Aug 2024 10:15:53 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id C6C6CDA7; Thu, 22 Aug 2024 03:15:32 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 58C063F66E; Thu, 22 Aug 2024 03:15:05 -0700 (PDT) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: akos.denke@arm.com, andre.przywara@arm.com, luca.fancellu@arm.com, mark.rutland@arm.com, maz@kernel.org Subject: [BOOT-WRAPPER v3 03/10] aarch64: Always enter kernel via exception return Date: Thu, 22 Aug 2024 11:14:34 +0100 Message-Id: <20240822101441.251184-4-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20240822101441.251184-1-mark.rutland@arm.com> References: <20240822101441.251184-1-mark.rutland@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240822_031549_201903_26E5B9D4 X-CRM114-Status: GOOD ( 10.40 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org When the boot-wrapper is entered at EL3 it will enter the kernel via ERET, and when entered at EL2 it will branch to the kernel directly. This is an artifact of the way the boot-wrapper was originally written in assembly, and it would be preferable to always enter the kernel via ERET so that PSTATE is always initialized to a known-good value. Rework jump_kernel() to always enter the kernel via ERET. Signed-off-by: Mark Rutland Acked-by: Marc Zyngier Reviewed-by: Andre Przywara Cc: Akos Denke Cc: Luca Fancellu --- arch/aarch64/boot.S | 32 +++++++++++++------------------- 1 file changed, 13 insertions(+), 19 deletions(-) diff --git a/arch/aarch64/boot.S b/arch/aarch64/boot.S index 52c617d..7449015 100644 --- a/arch/aarch64/boot.S +++ b/arch/aarch64/boot.S @@ -76,10 +76,6 @@ reset_at_el2: b.eq err_invalid_id bl setup_stack - mov w0, #1 - ldr x1, =flag_no_el3 - str w0, [x1] - bl cpu_init_bootwrapper bl cpu_init_arch @@ -111,18 +107,11 @@ ASM_FUNC(jump_kernel) bl find_logical_id bl setup_stack // Reset stack pointer - ldr w0, flag_no_el3 - cmp w0, #0 // Prepare Z flag - mov x0, x20 mov x1, x21 mov x2, x22 mov x3, x23 - - b.eq 1f - br x19 // No EL3 - -1: mov x4, #SPSR_KERNEL + mov x4, #SPSR_KERNEL /* * If bit 0 of the kernel address is set, we're entering in AArch32 @@ -130,13 +119,18 @@ ASM_FUNC(jump_kernel) */ bfi x4, x19, #5, #1 + mrs x5, CurrentEL + cmp x5, #CURRENTEL_EL3 + b.eq eret_at_el3 + cmp x5, #CURRENTEL_EL2 + b.eq eret_at_el2 + b . // Not possible + +eret_at_el3: msr elr_el3, x19 msr spsr_el3, x4 eret - - .ltorg - - .data - .align 3 -flag_no_el3: - .long 0 +eret_at_el2: + msr elr_el2, x19 + msr spsr_el2, x4 + eret